Generating system



Nov. 16,1948. WILSON 2,453,885

GENERATING SYSTEM Filed June 26, 1944 nlnlulHluh AVVENTOK N TfiEoooeE J l/V/LJ'ON Patented Nov. 16, 1948 GENERATING SYSTEM Theodore J. Wilson, Minneapolis, Minn., assignor to Minneapolis-Honeywell Regulator Company, Minneapolis, Minn., a corporation of Delaware Application June 26, 1944, Serial No. 542,100

8 Claims.

This invention relates to electrical generating systems and particularly to generating systems wherein provision is made for supplying a closely regulated voltage. The invention is particularly adapted for supplying a unidirectional potential of constant value.

It is an object of my invention to provide an improved electrical generating system capable of supplying an output voltage of relatively constant value.

It is a further object of my invention to provide a voltage regulating system devoid of any mechanically moving parts other than those of the generator itself, and one wherein the output voltage of the generator is regulated to a relatively constant value.

It is a further object of my invention to provide a low cost voltage regulating system of the thermionic type adapted to be manufactured economically in quantity and capable of furnishing satisfactory service over long periods of time, even when used under adverse conditions of vibration, dust, dirt or high altitudes.

It is a particular object of my invention to provide a regulating system devoid of any contacting apparatus inasmuch as such apparatus is disposed to failure under extreme conditions of altitude, low pressure, etc.

Other and particular objects of my invention are those inherently accomplished by the apparatus herein illustrated, described and claimed.

The apparatus is illustrated in the single figure of the drawing which is a wiring diagram schematically showing the electrical relationship of the various elements comprised in one embodiment of my invention.

Referring to the drawing, at l there is illustrated a generator of the direct current type having an armature |0a and a field l 0b, one terminal of the armature being connected to an output line I l at junction l and the opposite terminal being connected at junction l3 to ground l4, through line 2. One terminal of the field lllb is connected to junction l5 on output line H. The other terminal of the field is connected to one output terminal ll of the armature 20a of an accessory direct current generator 20. The remaining terminal Ila of 20a is connected through line 2| to junction 13 and thence to ground I4. The field 20b of the accessory generator is connected through lines 22 and 23 to output terminals 24 and 25 of a regulatory apparatus generally indicated by numeral 9 and hereinafter more fully described.

In the practice of my invention the main generator I0 and the accessory generator 20 are mechanically driven by any source of mechanical power generally designated by numeral which may be an internal combustion engine, a steam engine, an electric motor, or other suitable driver. The mechanical connection between driver 30 and generators l0 and 20 may be by a single shaft represented by the line 3i or it may be through any suitable mechanical connection such as a belt drive, if desired.

In the present embodiment of my invention the output line H is utilized for supplying a regulated unidirectional potential to any apparatus requiring a relatively constant voltage, for example, the battery A which is to be charged by the generator Ill. The positive terminal of battery A is connected to junction 26, and its negative terminal is grounded as at 21.

From junction 26 a line 32 extends to one terminal of resistor 34, the opposite terminal of which is connected at junction 35 to ground 36. Resistor 34 performs the function of a potential divider, and to that end is provided with an intermediate tap 38, which may be adjustable if desired, and to which is connected a line 39 which extends to the positive pole of a standard battery 40. The negative terminal of battery 40 is connected through line 4| to the grid 42 of a thermionic amplifier tube generally designated 45.

Tube 45 is provided, in addition to grid 42, with a plate 48 and a cathode 43 which is arranged to be heated by a filament heater 44. Cathode 43 is connected through line 46 to junction 35 and hence to ground 36. Plate 48 is connected through a potential divider 5| and a resistor 53 to ground at 54.

Plate potential for tube 45 is obtained from a power supply circuit generally indicated at BI and comprising potential divider 5!, a filter condenser 56, one secondary winding 10 of a transformer 2 described in more detail below, and a thermionic tube 62 which includes a plate 66, a grid 65, a cathode 63, and a heater filament 64'. The grid 65 and cathode 63 of tube 62 are shown electrically connected to permit the tube to operate as a half-wave rectifier. Potential divider 5| is connected to form the load resistor of this rectifier circuit, and filter condenser 56 is connected in parallel with the divider 5| by means of junction 58, conductor 59, junction 52, junction 50, conductor 49 and junction 51.

Under constant operating conditions, a substantially uniform D. 0. potential difierence is maintained around the end terminals of divider 5|: the ripple component of the rectified current is largely removed by condenser 56 if the latter is of sufficiently large capacitance. To the I. R, drop through divider 5! due to the flow of current in the rectifier circuit is added the drop due to flow of plate current in tube l5, the former drop being constant and the latter varying with change in the potential between grid 42 and cathode 43.

Of the total voltage drop through divider 5!, any desired portion may be taken off by adjustment of variable tap 55 for establishing the cathode potential above ground potential, of a pair of tubes 89 and 91.1 comprised in a generator field supply circuit, generally indicated at iili, which will be presently described. The control grid potential of these tubes is ground potential as will presently be set forth, and is therefore more negative than cathode potential, since it obtained through resistor 53 from the negative terminal of divider 5 i.

In addition to the two tubes just referred to, generator field supply circuit 86 includes filter condenser I24, one secondary winding [2% of transformer H2, and a phase shifting network generally indicated at [00. Tubes El! and ad are shown to be of the gas filled type and to comprise respectively, heater filaments 8i and 99, cathodes 32 and 92, screen grids 83 and t3, control grids 84 and 94, and plates 85 and as. A line H leads from tap 55 on divider 5! to the cathodes and screen grids of tubes 80 and 90, to establish the cathode potentials of tubes with respect to ground 54.

Transformer H2 has a primary winding i it which is suitably energized from any convenient alternating current source, controlled by a switch M3. The core of the transformer is illustrated at l M and is provided with a plurality of secondary windings, the function of winding Hi having been previously mentioned. Secondary winding iili serves to energize the heaters 4 5 and 64 of tubes 45 and 62, respectively. Secondary winding H8 similarly energizes the heaters 81 and 9! of tubes 80 and 90, respectively. Secondary winding is provided with a center tap lZl which is con nected to junction 24, previously mentioned, and through filter condenser HM to junction 25, the latter being connected, through line I26, to line 74 at junction 11. Winding l li is provided with end terminals [2! and 528. terminal l2"! being connected through line 129 to the plate 35 of tube all and terminal 128 being connected through line 30 to plate 95. Winding it! is center tapped as at 9'1, and is provided with terminals m2 and i i-i for energizing phase shifter me to provide adjustable A. C. bias potential for the control grids 84 and 94 of tubes 89 and 90.

Phase shifter I comprises a bridge circuit of which two adjacent arms are comprised by halves of secondary winder ill! the remaining arms of the bridge include a variable resistor m8 and an inductor I05. Inductor Hi and resistor 186 are connected together at one terminal Hi5 which is grounded as at i ll) through a current limiting resistor I69. To terminals H12 and H33, respectively, of secondary winding ID! are connected the other ends of inductor M15 and resistor Hi8. Terminals E02 and H33 are therefore the input terminals of bridge i252 and center tap 11 and terminal Hit are the output terminals of the bridge. Center tap 9'! of secondary winding ml is connected with the grids M and 8d of tubes 9!] and 80 by line 39. A resistor 8? is connected at junction 88 to conductor 89 and grounded con- 4 ductor M to act as input resistor for tubes 80 and 99.

The electrical characteristics of the inductor and resistor are so chosen according to principles well known to those skilled in the art that a signal potential appears between junction Hi6 and tap 9'! that is of a predetermined phase with respect to that across secondary WI, and by varying the value of resistor Hi3 from zero to infinity the phase angle between these potentials may be varied between 90 degrees and zero degrees. It will be observed that the output of secondary winding IE9 is oppositely impressed upon the plate of tubes Elli and Eli, while the output of phase shifter iiiil is simultaneously im pressed on the grids of both tubes.

From this arrangement it follows that by adjusting resistor Hit; the point in the cycle of plate potential at which tubes it and at discharge may be varied, the current flow through field winding 23b varying in the same manner. It will also be apparent that tubes 3E and til are arranged for full wave energization of the generator field 29b in response to the signal on the grid of tube it, as modified by the eifect of the A. C. bias provided by the phase shifter.

The operation of the apparatus heretofore described will now be set forth.

The system is started by closing switch M3. After the tubes warm up to a temperature at which emission can take place, power supply 6! operates to provide plate voltage for tube 45. The grid of tube 45 is at its most negative value, however, since there is no I. R. drop through divider 34 to buck the voltage of standard battery it. A minimum plate current therefore flows through tube 35, resulting in a minimum I. R. drop through divider iii-that due to operation of the rectifier being constant, For a given setting of tap 55, therefore, a minimum D. C. grid bias is applied to grids 3d and 9d, and if variable resistor I08 is in its position of minimum resistance, maximum plate current fiows through alternate tubes of the generator field supply on alternate half cycles of the current supplied to transformer H2, and maximum energization of field 28b is accordingly achieved.

Generator I0 is self-excited, and its field circuit includes armature a of auxiliar generator 20. When the driver 39 is started the voltage output of generator i0 is determined by the speed of driver it and the current through field Nib, the latter being additionally dependent on the output of generator 29 which is arranged to increase the current through field Iilb due to the operation of generator Mia. As operation of driver continues, voltage builds up between junction 25 and ground, and a portion of this voltage acts in the grid circuit of tube to buck standard battery 40, thus reducing the negative bias on the tube and permitting increased current to flow in the plate circuit through divider 58. Increased negative grid bias is therefore provided for generator field supply tubes 8-0 and Elli. and the plate current of these tubes is accordingly reduced, reducing the energization of field 20b and therefore the energization of generator ac. Thus, the increase in output of the main genera tor is continually opposed by decrease in its field excitation, until a point is reached at which further increase in output voltage is accompanied by such a decrease in excitation current as to reduce the output 01 the generator to its former value. Under these conditions, the circuit is in equilibrium, and of course in practice such equilibrium is very rapidly attained. The setting of tap 38 determined the output potential reached by the regulator system, by determining the magnitude of current flowing in field b to bring about this equilibrium for a given voltage of standard battery 40, and also makes it possible to compensate for changes in the voltage of the standard battery.

If the system is in equilibrium and the speed of the driver drops, the voltage output of generator l0 begins to decrease and the grid bias of tube therefore begins to increase. The current in field 201) immediatel increases as fully described previously, to build up the field in the main generator, so that the voltage returns to normal.

Similarly, if the voltage between junction 26 and ground increases, the grid bias in tube 45 decreases, the plate current in tube 45 increases increasing the bias on tubes 30 and 81!, the plate current in the latter tubes falls off, energization of generator field 20 is reduced, and the output voltage is again returned to normal.

Tap is effective to vary the amount of change in the grid bias on tubes and brought about by unit change in the voltage being regulated, and therefore acts as a sensitivity adjustment as opposed to the zero adjusting function performed by tap 38.

It will be realized that variations in the grid bias of tubes 80 and 90 affected by tap 55 also influence the point on the characteristic curve of these tubes at which they operate, since the plate voltage remains the same: this affects the efficiency of the regulator. possible to vary the sensitivity of this device Without at the same time varying its efiiciency, phase shifter I00 is provided. Bw adjustment of resistor I08, the portion of each cycle of the supply current during which tubes 80 and 9D discharge is varied. Therefore, a change in the voltage output due to adjustment of tap 55 may be compensated for to any desired extent by adjustment of resistor I08.

The structure and advantages of my invention have been fully and clearly set forth in the foregoing description, taken with the accompanying drawings, and the novel features thereof are pointed out in the appended claims. The disclosure, however, is illustrative only and I may make changes in detail, especially in matters of shape, size, and arrangement of parts, Within the principle of the invention, to the full extent indi cated by the broad general meanings of the terms in which the appended claims are expressed.

I claim as my invention:

1. A constant voltage direct current generating system comprising, in combination: a main generator having a main generator field; an accessory generator having an accessory generator field, said accessory generator being connected to supply a separate excitation potential to said main generator field; motor means for mechanically operating said main and accessory generators; and a control device comprising transformer means having a primary winding and a plurality of secondary windings, means adapted to energize said transformer with alternating current, a thermionic amplifier having cathode, anode, and con trol electrodes, rectifier means energizing the anode circuit of said amplifier from one of said transformer secondaries, a source of comparative potential, means acljustably connecting the output of said main generator, in opposed relation to said source of comparative potential, in the grid In order to make it circuit of said thermionic amplifier, an electronic full Wave grid controlled rectifier providing energization for said accessory generator field from said transformer, and adjustable means and responsive means including said thermionic amplifier controlling the operation of said grid controlled rectifier, said first named rectifier means including a resistor in said anode circuit.

2. A constant voltage direct current generating system comprising, in combination: a main generator having a main generator field: an accessory generator having an accessory generator field, said accessory generator being connected to supply a separate excitation potential to said main generator field; motor means for mechanically operating said main and accessory generators; and a control device comprising transformer means having a primary winding and a plurality of secondary windings, means adapted to energize said transformer with alternating current, a thermionic amplifier having cathode, anode, and control electrodes, rectifier means energizing the anode circuit of said amplifier from one of said transformer secondaries, a source of comparative potential, means adjustably connecting the output of said main generator, in opposed relation to said source of comparative potential, in the grid circuit of said thermionic amplifier, an electronic full wave grid controlled rectifier providing energization for said accessory generator field from said transformer, and adjustable means and responsive means including said thermionic amplifier controlling the operation of said full wave rectifier, said adjustable means including and second means energizing said fullwave rectifier from said transformer, said second means including means introducing time lag into cyclically varying currents passing therethrough, said responsive means including said thermionic amplifier.

3. A constant voltage direct current generating system comprising, in combination: a main generator having a main generator field; an accessory generator havin an accessory generator field, said accessory generator being connected to supply a separate excitation potential to said main generator field; motor means for mechanically operating said main and accessory generators; and a control device comprising transformer means having a primary winding and a plurality of secondary windings, means adapted to energize said transformer with alternating current, a thermionic amplifier, rectifier means energizing the plate circuit of said amplifier from one of said transformer secondaries, a resistor in said plate circuit, a source of comparative potential, means adjustahly connectin the output of said main generator, in opposed relation to said source of comparative potential, in the grid circuit of said amplifier, an electronic full wave grid controlled rectifier providing energization for said accessory generator field from said transformer, and adjustable means controlling the operation of said full wave rectifier, said last mentioned means including first and second means energizing said full wave rectifier from said transformer, said first means including said amplifier and said rectifier means, and said secand means introducin means including time lag into cyclically varying currents passing therethrough.

4. A constant voltage direct current generating system comprising, in combination: a main generator having a main generator field; an accessory generator having an accessory generator field, said accessory generator being connected to supply a separate excitation potential to said main generator field; motor means for mechanically operating said main and accessory generators; and a control device comprising transformer means having a primary winding and aplurality of secondary windings, means adapted to energize said transformer with alternating current,a thermionic amplifier,rectifier means energizing the plate circuit of said amplifier from one of said transformer secondaries, a variably tapped resistor in said plate circuit, a source of comparative potential, means adjustably connecting the output of said main generator, in opposed relation to said source of comparative potential in the grid circuit of said first amplifier, an electronic full wave grid controlled rectifier providing energization for said accessory generator field from said transformer, and responsive means adjustably controlling the operation of said full wave rectifier, said last mentioned means including said first amplifier, said rectifier and said resistor, said adjustable control being accomplished by variation. of position of the tap of said tapped resistor.

5. A dynamo-electric generator having an armature and field means, and a voltage regulator for controlling the energization of said field in accordance with the generated voltage; said regulator comprising, amplifier means, a source of comparative potential, a variable impedance connected to the output of said generator, means directly connecting said source of comparative potential between the input of said amplifier means and the variable portion of said variable impedance, a pair of gaseous discharge devices each including cathode, anode and control electrodes, normally energize-d transformer means, means connecting said transformer means with the cathodes and anodes of said devices to impress thereon alternating potentials in opposed phase relation, means connecting said devices with said field means to cause variations in the current through said field means, variable coupling means connecting the output of said amplifier to the cathode and control electrode of each of said devices, and a source of alternating volt age of adjustable phase connected with said variable coupling means to form a series circuit between the control electrode and cathode of each of said discharge devices whereby a, variation of said variable coupling or said alternating voltage of adjustable phase Will adjust the sensitivity of said voltage regulator and the variation of said variable impedance will adjust the generated voltage of said generator.

6. A direct current generator having an armature and field means, and a voltage regulator for controlling the energization of said field in accordance with the generated voltage; said regulator comprising, an amplifier, a variable impedance connected to the output of said generator to provide voltage adjustment therefor, a source of comparative potential connected between the input of said amplifier and the variable portion of said variable impedance, a. pair of gaseous discharge tubes each having a cathode, a plate and a control electrode, normally energized transformer means, means connecting said transformer to said tubes in a manner to energize the plates of said tubes in opposed phase relationship, variable coupling means connected between said amplifier and the control electrode and cathode of each of said tubes, an adjustable alternating current phase shifting device, means connecting said device to said transformer for energization therefrom, means connecting said device to said variable coupling means to form a series connection between the cathode and control electrode of each of said tubes to provide a sensitivity adjustment for said regulator, and means connecting the field means of said generator with said tubes for variable energization in accordance with the discharge of said tubes.

'7. A constant voltage direct current generating system comprising, in combination: a main generator having a main generator field; an accessory generator having an accessory generator field, said accessory generator being connected to supply a separate excitation to said main genorator field; and a control device comprising normally energized transformer means, an amplifier having cathode, anode and control electrodes, a source of comparative potential, means adjustably connecting the output of said main generator in opposed relation to said source of comparative potential in the grid circuit of said amplifier, a full Wave grid controlled rectifier connected to said transformer for providing energization for said accessory generator, adjustable means connecting said amplifier to said rectifier to cause variable energization thereof, and an adjustable phase shifting means connected in F circuit with said last named adjustable means for controlling the sensitivity of said full Wave rectifier.

8. In a device for regulating the field energization of a dynamo-electric generator in accordance with the relation between the generated voltage and a standard voltage, in combination: voltage comparison means for comparing the relation between the generated voltage and the standard Voltage for controlling the fiow of current through a first electron discharge device; a pair of phase sensitive electron discharge means continuously energized with alternating voltage for variably energizing the field; a source of al-- ternating biasing voltage of manually adjusted phase independent of said voltage comparison means for making adjustment of the conductivity of said pair of discharge means; and means including said first discharge device for variably biasing said pair of discharge means in accordance with the voltage derived from said voltage comparison means.

THEODORE J. WILSON.

REFER-EN CF15 CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,005,892 Gulliksen June 25, 1935 2,966,943 Philpott Jan. 5, 1937 2,234,747 Crever Mar, 11, 1941 2,154,354 Ranson Apr. 11, 1939 Certificate of Correction Patent No. 2,453,885. November 16, 1948.

THEODORE J. WILSON It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows:

Column 5, line 38, for Bw adjustment read By adjustment;

and that the said Letters Patent should be read with this correction therein that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 26th day of April, A. D. 1949.

THOMAS F. MURPHY,

Assistant Commissioner 0 f Patents.

Certificate of Correction Patent No. 2,453,885. November 16, 1948.

THEODORE J. WILSON It is hereby certified that error appears in the printed specification of the above numbered patent requirlng correction as follows:

Column 5, line 38, for BW adjustment read By adjustment;

and that the said Letters Patent should be read with this correction therein that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 26th day of April, A. D. 1949.

THOMAS F. MURPHY,

Assistant Commissioner of Patents. 

